code: def test_build_single_handler_application_unknown_file() -> None:
      with tempfile.NamedTemporaryFile(suffix=".bad") as f:
          with pytest.raises(ValueError) as e:
              util.build_single_handler_application(f.name)
      assert (
          "Expected a '.py' script or '.ipynb' notebook, got: "
          in str(e.value)
      )
  
file_path: bokeh/tests/unit/bokeh/command/test_util__command.py
imports: from __future__ import annotations
  import pytest
  import os
  import tempfile
  from unittest.mock import MagicMock, patch
  from tests.support.util.types import Capture
  import bokeh.command.util
label_desc: Use image node_id 2 for calling a global function with example usage: test_build_single_handler_application_unknown_file() without return types